A study by an international panel of scientists shows that the researchers are confident about the links between human activity, global warming and climate change.

The usually well-behaved ribbon of high winds that runs eastward across North America has wandered all over the place recently, and even split in two. That's caused a whole host of extreme weather in the Northern Hemisphere, including the recent rains in Colorado, bitter cold in Florida and a heat wave in Alaska.

Scientists are about to deliver another major assessment of climate change. The report from the Intergovernmental Panel on Climate Change involved hundreds of scientists from around the world and has left some of them wondering whether there's a more effective way to put the document together.